Thesis Abstract

                  ABSTRACT

A solar closed air Brayton cycle, with rated power of 50 MW, was considered. The system is composed of a concentrating solar tower with volumetric receiver, an intercooling and regenerating gas turbine and an evaporative tower cooling system. The characteristic feature of the system is a control strategy able to adjust the plant in a large range of load, maintaining net electric conversion efficiency almost constant. The concentrating solar power (CSP) plant operates without adding fuel and can heat air up to a maximum temperature of 850 °C, at the solar tower outlet. The numerical analysis was performed by SAM for the solar tower and by Thermoflex © for the assessment of the performance of the whole system. The thermal energy input was calculated on the basis of the DNI of the TMY from Seville. Results show an electricity production greater than 75GWh per year, with a significant sparing fossil fuel consumption and avoided CO2 emissions.

Thesis Overview

1.0 INTRODUCTION

1.1 BACKGROUND STUDY 

The solar source, as known, is not a resource that ensures regularity of energy production; consequently, its random nature leads to the search of systems able to capture the incident energy on the terrestrial sphere in an effective and continuous manner. A particular category of systems that are suitable for this application and are currently being developed in installations at an experimental stage [1] [7], or in certain cases also commercial [2] are known as concentrating solar Brayton cycle. They are promising in term of efficiency, low emissions and limited consumption of cooling water.

To compensate the lack of thermal power during the clouds transient, generally in this kind of systems fuel is used by combustors to make always at nominal values the operating point. In this article the possibility of combining an innovative control system for a solar concentrator closed intercooled regenerated Brayton cycle, is analysed. Among the expected benefits of such a system, there is a good energy yield, which is almost constant regardless of the intensity of solar radiation, without the emission of greenhouse gases. This technology, in fact, avoids the use of combustors, and thus it increases the heat energy from fossil fuels, ensuring, at the same time, a large margin of regulation 

  Nomenclature 

 Product of heat exchange coefficient global for the exchange surface 

Avg  Average value calculate for every months Opt 

Opt  Optimal value i Represent the number of the month on thesum ܲ 

P. Average pressure of the air on cycle 

Vc  Volume control MW Molecular weight of the air 

R  Universal constant of ideal gases 

T  Average temperature of the air in the principal cycle 

TIT  Temperature Intel Turbin